Amorphous Vanadium Oxides with Dual ion Storage Mechanism for High-Performance Aqueous Zinc ion Batteries.

Owing to the extremely limited structural deformation caused by the introduction of guest ions that their rigid structure can sustain, crystalline materials typically fail owing to structural collapse when utilized as electrode materials. Amorphous materials, conversely, are more resistant to volume expansion during dynamic ion transport and can introduce a lot of defects as active sites. Here, The amorphous polyaniline-coated/intercalated V2O5·nH2O (PVOH) nanowires are prepared by in situ chemical oxidation combined with self-assembly strategy, which exhibited impressive electrochemical properties because of its short-range ordered crystal structure, oxygen vacancy/defect-rich, improved electronic channels, and ionic channels. Through in situ techniques, the energy storage mechanism of its Zn2+/H+ co-storage is investigated and elucidated. Additionally, this work provides new insights and perspectives for the investigation and application of amorphous cathodes for aqueous zinc ion batteries.

Reunderstanding the Reaction Mechanism of Aqueous Zn-Mn Batteries with Sulfate Electrolytes: Role of the Zinc Sulfate Hydroxide.

Rechargeable aqueous Zn-Mn batteries have garnered extensive attention for next-generation high-safety energy storage. However, the charge-storage chemistry of Zn-Mn batteries remains controversial. Prevailing mechanisms include conversion reaction and cation (de)intercalation in mild acid or neutral electrolytes, and a MnO2 /Mn2+ dissolution-deposition reaction in strong acidic electrolytes. Herein, a Zn4 SO4 ·(OH)6 ·xH2 O (ZSH)-assisted deposition-dissolution model is proposed to elucidate the reaction mechanism and capacity origin in Zn-Mn batteries based on mild acidic sulfate electrolytes. In this new model, the reversible capacity originates from a reversible conversion reaction between ZSH and Znx MnO(OH)2 nanosheets in which the MnO2 initiates the formation of ZSH but contributes negligibly to the apparent capacity. The role of ZSH in this new model is confirmed by a series of operando characterizations and by constructing Zn batteries using other cathode materials (including ZSH, ZnO, MgO, and CaO). This research may refresh the understanding of the most promising Zn-Mn batteries and guide the design of high-capacity aqueous Zn batteries.

Why does the capacity of vanadium selenide based aqueous zinc ion batteries continue to increase during long cycles?

At present, rechargeable aqueous zinc ion batteries (RZIBs) have become a rising star and highly sought after in the field of new energy. While vanadium-based RZIBs often exhibit an anomaly of increased long-cycle capacity, which has not been explored in depth. Nevertheless, it is critical to understand this phenomenon to develop high-performance RZIBs. Therefore, this study investigated the growth mechanism of VSe2-based RZIBs using VSe2/MXene as the cathode material via in-situ and ex-situ characterization techniques and electrochemical measurements. Experimental results indicated that with the interaction/extraction of Zn2+/H+ in the host material during cycling, an obvious oxidation reaction occurs at high voltage, and the formed vanadium oxide further reacts with Zn2+ from the electrolyte. As a result, Zn0.25V2O5·H2O is continuously produced and accumulated, contributing to the increasing capacity of the prepared RZIBs.

A self-healing neutral aqueous rechargeable Zn/MnO2 battery based on modified carbon nanotubes substrate cathode.

Rechargeable aqueous Zn/MnO2 batteries show great potential for grid-scale storage due to their low cost, high safety, and energy density, yet suffer from continuous capacity decay during operation. Therefore, this work proposes a capacity self-healing aqueous Zn/MnO2 (Zn/cCNTs-MnO2) battery using carboxyl-modified carbon nanotubes (cCNTs) as the cathode substrate, ZnSO4 + MnSO4 mixed aqueous solution as the electrolyte, and Zn foil as the anode. Based on the controllable electrodeposition reaction of MnO2, the specific capacity of Zn/cCNTs-MnO2 batteries can be achieved or recovered by operating several cycles under a low current density (0.1 mA cm-2). Then, the batteries can stably perform under a high current density (1 mA cm-2). By repeating the above steps, a capacity self-healing usage scheme was established, which can significantly improve the cycling performance of Zn/cCNTs-MnO2 batteries. Moreover, the results of the proposed Zn/cCNTs-MnO2 batteries verify the MnO2 electrodeposition mechanism and introduce a novel method for the development of durable aqueous rechargeable Zn/MnO2 batteries.